This application is related to and claims priority under 35 U.S.C. xc2xa7119 from Japanese Patent Application Nos. Hei 9-07506 and Hei 10-063373, incorporated herein by reference.
The present invention relates to automobile weatherstripping which includes an extrusion-formed part and a mold-formed part and in which the mold formed part is welded and integrated with the extrusion-formed part.
An olefin elastomer which is represented by ethylene propylene non-conjugated diene rubber (EPDM) has a small specific gravity and contains substantially no unsaturated bonds. Therefore, it is easy to satisfy a demand for a reduction in weight and an increase in weather resistance. For this reason, it has hitherto been widely used as a forming material of automobile weatherstripping (referred to simply as xe2x80x9cweatherstrippingxe2x80x9d hereinafter).
The weatherstripping was conventionally manufactured, for example, by cutting an extrusion vulcanized formation consisting of an EPDM rubber blend, setting the resulting material with respect to a mold from one side, both sides, or multiple sides, and injecting the rubber formed material into a cavity to thereby perform vulcanization mold forming.
On the other hand, it has been considered to use, as material for use in this mold forming, nonpolar thermoplastic polyolefin- or styrene-based elastomer or the like necessitating no vulcanization step in place of the EPDM from the viewpoint of productivity (see, e.g., Japanese Patent Laid-Open Publication No. Sho 59-159329).
However, in general, it is difficult to obtain a practical bonding strength between the extrusion-formed part, which is an EPDM vulcanized formation, and the thermoplastic elastomer (hereinafter referred to as xe2x80x9cTPExe2x80x9d) mold-formed part. Therefore, it is necessary to interpose a bonding agent layer between the extrusion-formed part and the mold-formed part and, therefore, the use of such an elastomer is still difficult to use to satisfy the demand for enhanced productivity.
In view of the above problems of the prior art, it is an object of the present invention to provide automobile weatherstripping which has a sufficient level of bonding strength between the extrusion-formed part an the mold-formed part even with no bonding agent layer interposed therebetween.
To attain the above object, according to the present invention, automobile weatherstripping has an extrusion-formed part and a mold-formed part, the mold-formed part being welded and integrated with the extrusion-formed part, where the extrusion-formed part is made of an olefin elastomer and the mold-formed part is made of a resin composition containing the following components (A) to (E) below (provided, however, that the sum total of (A) to (E) is 100 parts by weight).
(A) an olefin resin of 5 to 50 parts by weight;
(B) an ethylene-xcex1-olefin copolymer rubber 5 to 86 parts by weight;
(C) a hydrogenated aromatic vinyl conjugated diene compound block copolymer of 2 to 30 parts by weight;
(D) at least one component selected from the group consisting of natural rubber, isoprene rubber and butadiene rubber of 2 to 40 parts by weight; and
(E) a mineral oil of 5 to 80 parts by weight.
As will be supported by examples as described later, the weatherstripping according to the present invention enables the procurement of a sufficient level of bonding strength between the extrusion-formed part and the mold-formed part even with no bonding agent layer being interposed therebetween. Accordingly, in the present invention, it becomes possible to manufacture the weatherstripping with high productivity.
Also, the weatherstripping of the present invention has excellent follow-up flexibility, sealing properties and mechanical strength at the portion of a corner (mold-formed part) of, for example, weatherstripping a door. Accordingly, the weatherstripping of the present invention is excellent in terms of the performance of the mold-formed part.